DISPOSITIF ET METHODE D'ETRANGLEMENT SANS BLOCAGE D'UN FLUX DE MATIERES EN SUSPENSION

DEVICE AND METHOD FOR THE NON-CLOGGING THROTTLING OF A FLUID STREAM OF SUSPENDED MATTER

Abrégé français

L'invention se rapporte à une valve ou à un dispositif d'étranglement pour un flux liquide, et en particulier un flux contenant des matières solides, comme un flux de suspension pâteuse. La valve possède les caractéristiques suivantes : un corps creux de symétrie sensiblement rotationnelle, qui est traversé par le liquide; le corps creux présente une zone de passage variable qui est d'une symétrie sensiblement rotationnelle; et un sens principal de flux qui est substantiellement parallèle à l'axe longitudinal du corps creux est prévu dans le corps creux. Une alimentation en liquide à la zone de passage est prévue, de sorte qu'une composante de rotation autour du sens du flux principal soit ajoutée au liquide en ce qui concerne le sens du flux principal.

Abrégé anglais

The invention relates to a valve or throttling device for a fluid flow, and particularly a flow containing solids, like a flow of pulp suspension. The valve has the following features: A hollow body of substantially rotational symmetry, which is traversed by liquid; the hollow body has a variable passage area which is substantially of rotational symmetry; and a main direction of fluid flow which is substantially axial to the longitudinal axis of the hollow body is provided in the hollow body. A liquid feed to the passage area is provided so that a component of rotation around the direction of the main stream is added to the liquid with reference to the direction of the main stream.

Revendications

CLAIMS:
WHAT IS CLAIMED IS:
1. A device for throttling a fluid stream containing solids, the device
comprising:
a hollow body of substantially rotational symmetry and having a longitudinal
axis,
the body being traversed in an axial direction by the fluid stream;
the hollow body having a variable passage cross section which is of
substantially
rotational symmetry;
a means feeding the fluid stream to the passage area and a means for directing
the
fluid fed so that in addition to traveling substantially axially of the hollow
body, the fluid
has a rotary component around the main direction of the stream through the
hollow body;
and
the body having an outlet for the liquid.
2. The throttling device of claim 1, wherein the means for directing the fluid
comprises the means for feeding the fluid to the throttling device
communication into the
hollow body generally tangentially to the body of rotational symmetry which is
generally
cylindrically shaped.
3. The throttling device of claim 1, including fluid wetted surfaces therein
shaped
and positioned for causing rotation of the fluid around the hollow body.
4. The throttling device of claim 1, further comprising a throttle piece in
the hollow
body for defining a narrowed cross section annular space between the throttle
piece and
the hollow body.
5. The throttling device of claim 4, wherein the body of rotational symmetry
has a
constriction in its cross section downstream in the fluid path of the throttle
piece in the
body.
8

6. A method for reducing the tendency toward clogging of a valve or throttling
device, wherein the valve or throttling device has a hollow body of
substantially
rotational symmetry about a longitudinal axis;
the method comprising moving liquid through the body generally in a direction
substantially axially with reference to the longitudinal axis of the hollow
body;
imparting a rotary component to the liquid flow entering the body so that the
liquid rotates in the body with respect to the axial direction of the liquid,
and imparting
the rotary component of motion to the liquid at least in a region of throttled
cross section
in the hollow body; and
permitting the liquid to exit from the hollow body after passing the region of
throttled cross section.
7. The method of claim 6, wherein the rotary component is imparted to the
liquid
stream by supplying the liquid stream tangentially to the hollow body upstream
of the
throttled cross section.
8. The throttling device of claim 1 for use with a headbox for a paper making
machine, the headbox having a pulp suspension feed thereto and an exit
therefrom;
wherein the feed includes a throttling device, said device being positioned in
the pulp
suspension feed to the headbox.
9. A throttle apparatus in a conduit for supplying a material suspension to
the
headbox of a paper machine with the following characteristics:
there is provided a rotationally symmetrical hollow body for fluid flow-
through,
the body having a longitudinal axis;
the hollow body including a narrowed region;
there is provided a main flow direction which in essence runs axially with the
longitudinal axis of the hollow body; the apparatus is characterized by the
following
features;
9

a fluid supply is provided such that the fluid, relative to the main flow
direction, is
given a rotational component encircling the main flow direction, so that
clogging is
avoided.
10. A throttle apparatus according to claim 9 characterized in that, the
hollow body
has a variable flow-through surface which is essentially rotationally
symmetrical.
11. An apparatus according to claim 9, characterized in that, the supply of
the throttle
apparatus is disposed tangentially in a cylindrically configured space.
12. An apparatus according to one of claims 9 to 11, characterized in that,
the fluid-
wetted surface of the valve is at least partly provided with a structure which
generates
rotation in the fluid.
13. A process for reducing the clogging tendency of a valve or a throttle
apparatus
having a narrowed region and provided in a conduit for supplying a material
suspension
to a headbox of a paper machine, characterized in that, a rotational component
relative to
the main flow direction is added to the suspension in a region of throttled
cross-section..
14. A process according to claim 13, characterized in that, the suspension
flow is fed
tangentially with respect to a longitudinal axis of the conduit.
15. A process according to claim 13 or 14, characterized in that, all
generation of
fibre wipings is avoided.
16. A method for reducing clogging of a valve or throttling device for a paper-
making
maching having a headbox, wherein the valve or throttling device has a hollow
body of
substantially rotational symmetry and having a longitudinal axis defining a
main
direction of fluid flow;
the method comprising the steps of:
10

moving fluid through the body generally in a direction substantially along the
longitudinal axis of the hollow body;
imparting a rotary component to the fluid flow entering the body so that the
fluid
rotates in the body with respect to the longitudinal axis, and imparting said
rotary
component of motion to the fluid at least in a region of a throttled cross
section in the
hollow body, the region of throttled cross section being positioned in the
pulp suspension
feed to the headbox of the papermaking machine; and
permitting the fluid to exit from the hollow body after passing the region of
throttled cross section.
17. The method of claim 16, wherein the rotary component is imparted to the
fluid
flow by supplying the fluid flow tangentially to the hollow body upstream of
the throttled
cross section.
18. The method of claim 17, wherein the rotary component is imparted to the
fluid
flow by introducing the fluid into the hollow body at an inlet disposed
eccentrically and
substantially perpendicularly to the longitudinal axis of the hollow body.
19. A method for reducing clogging at a region of narrowed cross-section of a
throttle device in a fluid line conveying a fluid flow to a headbox in a
papermaking
machine, the throttle device having a longitudinal axis and adapted for a main
fluid flow
in a direction of the longitudinal axis, the method comprising the step of:
imparting at least in the vicinity of the region of narrowed cross-section a
rotational component to the fluid flow which is rotational about the direction
of the main
fluid flow, for reducing clogging of the throttle device by an accumulation of
any
suspensions in the fluid flow.
20. The method of claim 19, wherein the imparting step comprises feeding the
fluid
flow in the throttle device in a direction tangential to the longitudinal
axis.
11

21. The method of claim 19 wherein fibers are suspended in the fluid flow, and
the
fluid is fed so as to avoid fiber accumulation in the throttle device.
22. A device for throttling a fluid stream containing solids in a paper-making
machine having a headbox, the device comprising:
a hollow body of substantially rotational symmetry and having a longitudinal
axis,
the body being traversed in the direction of the longitudinal axis by fluid
and, the
longitudinal axis defining a main direction of fluid flow;
the hollow body having a variable passage cross section which is of
substantially
rotational symmetry;
means feeding fluid to the passage area and for directing the fluid fed so
that in
addition to traveling substantially along the longitudinal axis of the hollow
body,
the fluid has a rotary component around the main direction of fluid flow
through
the hollow body; and
the body having an outlet for the fluid;
the device being positioned in the pulp suspension feed to the headbox of the
paper-making machine.
23. The throttling device of claim 22, wherein the means for directing a
rotary
component to the fluid comprises the means feeding fluid to the throttling
device
communicating into the hollow body generally tangentially to the body of
rotational
symmetry which is generally cylindrically shaped.
24. The throttling device of claim 22, including fluid wetted surfaces therein
shaped
and positioned for causing rotation of the fluid around the hollow body.
25. The throttling device of claim 22, further comprising a throttle element
in the
hollow body for defining a narrowed cross section annular space in the hollow
body
between the throttle element and the hollow body around the throttle element.
12

26. The throttling device of claim 25, wherein the body of rotational symmetry
has a
constriction in its cross section downstream in the main direction of fluid
flow of the
throttle element in the body.
27. A throttle device for use in a fluid line conveying a fluid flow to a
headbox in a
papermaking machine, the throttle device comprising:
a substantially rotationally symmetric hollow body having a longitudinal axis
and
adapted for main fluid flow in a direction along the longitudinal axis, the
hollow body
having a region of narrowed cross-section;
means for imparting at least in the vicinity of the region of narrowed cross-
section
a rotational component to the fluid flow which is rotational about the
direction of the
main fluid flow, for avoiding obstructions by an accumulation of any
suspensions in the
fluid flow at the region of narrowed cross-section.
28. The throttle device of claim 27, wherein the hollow body has a fluid flow
passage
of variable cross-section which is substantially rotationally symmetric.
29. The throttle device of claim 27, wherein the imparting means includes
means for
feeding fluid to the throttle device in a direction tangential to the main
fluid flow.
30. The throttle device of claim 27, wherein the imparting means comprises
inner
surfaces of the hollow body adapted to contact the fluid flow there-past, the
inner
surfaces being configured to impart a rotational component to the fluid flow
past the
inner surfaces.
31. A throttle device for use in a fluid line conveying a fluid flow to a
headbox in a
papermaking machine, the throttle device comprising:
a substantially rotationally symmetric hollow body having a longitudinal axis
and
adapted for a main fluid flow in a direction along the longitudinal axis, the
hollow body
having a region of narrowed cross-section;
13

a fluid flow device imparting at least in the vicinity of the region of
narrowed
cross-section a rotational component to the fluid flow which is rotational
about the
direction of the main fluid flow, for avoiding obstructions by an accumulation
of any
suspensions in the fluid flow at the region of narrowed cross-section.
14

Description

- P/14-333
- - 1 -
DEVICE AND MBTHOD FOH THE NON-CLOfiGINt3 THROTTLING
OF 71 FLiIID $TRg7Vt DZ' SUSPENDED MhTTER
B1~CRGROUND OF THE INVENTION
The present invention relates to a device and a
method far the ncn-clogging throttling of a fluid Stream,
particu?arlv a stream of suspended pulp in a paper
machine or a pulp preparation plant.
Valves of many different types are known in the
prior art for throttling fluid streams, including ball
valves, flap valves, needle valves, and the like. An
essential disadvantage of these valves is that they
provide relativ~a narrow cross sections for establishing a
desired rate of Ilow. It is Known that narrow cross
sections tend to clog in an undQxirable msnnex upon tho
passage or pulp suspensions and, upon theix use in paper
making machines, they procuce fiber uripi.ngs, local
accumulations of fibers and deposits. This either
results in clegging of the valvo or elc~ fiber wipingc or
deposits are not bro:~ten up again before the start of the
sheet forming process duo to the absence of the influence
of shearing forces. As a xesult, in the most favoxabhe
case, formation flown are formed in the paper web.
However, experience shows that these non-homogeneous
elements in the sheet are fregutntly the starting point
for tearing of the entire web of paper and they thus lead
to. significant disturbances in the operation of a paper
machine.
srrx11i2;32

.._ - 2
2l~'~40'~
S',TMI'2ARY. OIL' THE I:WENTION
The object of the invention is to provide a
z°alva or a throttle member, in which t'rrQ formation of
fiber wipings and/or the danger of clogging is avo~,ded by
a suitable design.
The invention concerns a valve or throttling
devioe for a fluid stream, particularly a solid
conducting stream, and more particularly a fluid stream
of pulp suspension in the headbox of the paper making
machine. The valve or throttling device includes a
t hollow body of s~,:bstantially rotational sy:nnetry having a
longitudinal axis along the direction of liquid flow
through the body. The hollow body also includes a
variable cross section passage area which is of
substar_tially rotational symmetry. A throttle piece may
be provided in the body to defin8 a narrow cross section
annular throttle region through which the solid
conducting stream passes and where the solid conducting
stream rnigrt be blocked. Means, e.g. in the form of
2o tangential inlet flow to the hollow body, era provided to
impart a rotary component of flaw to tl~e liquid being fed
into the hollow body and being fed peat the throttle area
of the body, so that the liquid has a rotary component
around th= direction cf the main stream as the r.~tain
stream moves through the hollow body to the outlet from
the throttle device. othor means may be pro'trided for
providing the rotary component ~.o the liquid flow. For
example, the inner surfaces of the respective devices are
to be grovided with e.g. helical grooves, guide vanes
etc. which cause xota,tion Or the liquid.
The invention also concerns the method of
reaucing clogs in a valve or throttling crevice through
spEC~82132

3 - 212'7~U
imparting the rotary component of motion to the liquid
stream passing through the hollow body.
The inventors have recognized that the tenderiCy
of a valve toward clogging can be considerably reduced.
particularly in a type of valve construction which
corresponds to a needle valve, if a rotary component is
added to the flaw in the region of the narrowest point of
the valve. The rotary component breaks up any
turtaulences which may be present and also the fiber
ip wipings and,/or fiber accumulations thereby produo~a,
w:~ich might otrerwise lead to clogging.
Other features and advantagl~C of the pros~nt
invention will become apparent from the following
description of the -ynvontion which refers to the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
fig. 1 is a diagrammatic cross section through a valve
in accordance with the invention;
Fig. 2 is a section A-A through the valve oZ the
' irwention shoran in Fig. I;
Fig. 3 shows the ,ass of the valve or the invention in
the pulp-suspension feed of a headbox.
DFTA_TT_,ED DESGRT_ TTON OF EMBODI;~,' ~E. TS OF TIdF INVkNTIDN
Fig. 1 is a cross-sectional view of a throttle
device 1 in accordance with tho inv~ntion. In the
diagrammatic showing, the throttle device includes a body
which definss a cylindrical nollow e~pace of substantially
rotational symmetry having a constriction 3. A fluid
stream i~c fod in perpQndioular to the axis of the
3o cylindrical hollow space via an eccentrically arranged,
radius parallel feed 4. The fluid stream S thus enters
s~~8siaz

- 4 - 21~"~~~~
the hollow space t,angentinlly and is there deflected
towarw the axial direc~ion along the hollow space which
dire~t~on is along the axis of the space. Triis imparts a
spiral course to the stream S withir, the cylindrical
hallow space. wi~hir. iris hollow space there .is also an
axially arranged ray 2. IL is provided with a widening
ors its lower side, which is the side facing the throttle
ox constriction 3. The ram :~ is displaceable in the
axial airection so that a narrowed annular restriction in
cross Section similar to that provided by a needlQ valve
i5 effected by axial displacement of the ram. In
contrast to an ordinary naodlo va~.ve, however, the
tangentially introduced stream s~;ffieiently flushes the
narrowed constriction era that no clogging by solids
entrained in the flow should occur at this point. This
is partioularly advantageous in connection with streams
of suspender. pulp .n paper machines in which such
clogging, and therefore formations of fiber wipings, can
have vexy unfavorable e~fects on the quality of the paper
produced.
The liquid exits through an outlet at thQ
bottom of the body 1.
Fig. 2 is a cross suction A-A through the
throttle Qevice of dig. Z. In the top view' shown, the
tangential feed of the stream s into tho c~~lindxical
inner space at the throttle device is clearly shown.
The invEntion is not lzmitod tc a purely
tangential feed of the stream into the throttle space of
a throttling device. 2t is also possible, for instance,
o to use suitable ball elements to change the direction of
the stroam fed within the entire solid angle so that, on
the one hand, an angle other than 90° with respect to the
mai:a axis og the throttling device can be adopted and at
srnc~~~sax

_ s _
the same time the eccentricity of the stream of pulp with
respect to the axis of the cylindrical throttling device
car. be controlled. In this weLy, simple control of the
angle of the rotating flow spiral within the thrott.inq
device is possible. As a result, on the one hand, t2-.e
cleanwng effect can be controlled in a desired manner
and, an the other hand, an add~.tional iriCredse or
xedu4tion of the throttling is possible without the
reduced passage area F having to be ;:rianged by moving or
ZO changlnq the ram 2.
Furthermore, the fluid wetted surfaces may be
surfaces for causing ratatien of the liquid. To da this,
the inner surfaces of the respective devices are to be
pravidod with e.g. helical groav4e, guides vanes etc.
which cause rotation of the liquid.
Fig. 3 chawa the use of the valve of Fige. 1
and 2, for example or the controlled feeding of dilution
water into the main atr4am of tho pulp suspension in a
paper machine headbox. T-~o cross-flow distributors Q1
and Q2 are shown, the pulp susponsion being fed in
slightly increased concentration from the cross-flew
distributor Q1 via a main line H to the headbox STA.
There are two distributors, each comprising a
main pipe, extending in rne cross direction or the
nachine and from open side of the headbox to the other
one. Each main pipe is connected to a p~,u:ality or small
diameter pipes, each of which generally is located in a
vertical plane situated perpendicularly can the length
axis of the main pipQ. Tha small diarn~ter pipes are
3o arranged one behind the other one, a5 se~ri In d Sl.de
alevational view.
The two-distributor-versyon comprises two such
distributors, urith the main pipes being located side by
&w'BCSpZL3~

- ~ - 2~~'~~~~
tide and parallel to oaoh other, trh~raioy any one of the
small d=ameter pipes of the second distributor is
cor.neoted to one single one of the small diameter pipes
of t:~e first distrib~.~tor. Normally, tre maid pipe of the
3 seoond distributor has a smaller diameter than the main
pipe of the first distributor.
on the main line H, a feed of dilution water
into the rain stream H at an angle other than 90° is
shovrn. The feed consists essentially og the throt:.le
1o elemer_~t 2 itself, the throttle element having the same
development as the one shown in fig. z and being
connected via its feed Iine dire,otly to the second cross-
flo~w distributor ~z rahlch conducts the dilution water.
~y tre correct selection of the angle batwraan the main
1~ stream H and the secondary stream N fed by the throttling
dQVICA, tho rr~sult is obtain~d th-rt, xagaxdlacs pf the
amount of the secondary stream N fed, the sum of the
amount of suspension f~d to the headbox r~_n.ains constant.
By the development of the throttle d~2vice Z, any
2o formation of fiber wiping in the throttle devise ie
avQ,~'.ded, avoiding reduction in the q~:ality of the paper
produced. 1'he throttle device 7. is operated in such a
nanner t:~at, at the normal operating point, an average
amount of pulp suspension is fed by the throttle device
25 1, so that no settling processes o~ solids in the
throttle device are possible. The regulation of the
density of the pulp, and therefore of the concentration
of the total suspension Zxom streams N and H, then takes
placQ around this central operating point_ Ths sum of
3~ the total flow remains constant, and a verl~ sensitively
adjusted regulaticn of the concentration is obtained as a
result o: the canstracti~n of the throttle device 1.
sPrecvesi3Z

' - 2~.2'~~(3~
Although the prnsant inv~ntion hao~ boon
described in relati4ri to a particular embodiment thereof,
many other variations and mcdificatyone and other uses
will became appaxer.t to those skilled in the art. It is
pre~arrQd, t~xerefore, that the present invention be
limited not by the apeci.~~_c discla5ure herein, but only
by the. appended claims.
SPEC182132

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